Presently, in 3GPP, the standardization of LTE-advanced, which is an enhanced system of LTE (Long Term Evolution) (also referred to as “LTE Release 8” (Rel. 8), is in progress (hereinafter the specifications of LTE Release 10 (Rel. 10) and later versions will be collectively referred to as “LTE-A”).
In radio communication systems such as LTE and LTE-A (LTE Rel. 8-11), uplink transmission power control to use both open-loop control and closed-loop control is introduced (see, for example, non-patent literature 1). To repair the path loss between user terminals and radio base stations, open-loop control is executed based on the path loss calculated by the user terminals and parameters reported from the radio base stations to the user terminals on a semi-static basis. For example, these parameters are reported to the user terminals through higher layer signaling such as RRC (Radio Resource Control) signaling.
On the other hand, closed-loop control is executed in order to maintain the received quality of an uplink shared channel (PUSCH: Physical Uplink Shared Channel) and an uplink control channel (PUCCH: Physical Uplink Control Channel) in radio base stations, based on TPC (Transmission Power Control) commands reported from the radio base stations to user terminals on a dynamic basis. TPC commands represent values to increase and decrease transmission power, and are included in, for example, downlink control information (DCI: Downlink Control Information) that is transmitted in downlink control channels (PDCCH (Physical Downlink Control Channel) and EPDCCH (Enhanced Physical Downlink Control Channel)).